Numerical analysis of wells turbine aerodynamics

Ocean wave power can be harnessed by means of a Wells turbine driven by a b i-directional airflow above an oscillating water column. While the Wells tu rbine research budget remains small, full-scale experiments are prohibitive ly expensive. Computational fluid dynamics (CFD) is a possible way of gener ating full-scale data. This paper summarizes a numerical study of Wells tur bine performance and aerodynamics using a CFD method, and makes recommendat ions about its use for Wells turbine studies, Calculations have been perfor med for a monoplane turbine comprised of straight NACA 0015 blades at a sta gger angle of 90 deg, Reynolds number 8 x 10(5), tip Mach number 0.4, and h ub-to-tip ratio 0.6. Flow coefficient, tip clearance, and blade number were varied. The predictions agree favorably with experimental data. Difference s can he explained partly by geometric differences between the experimental and numerical turbines. Because of the 90-deg stagger angle of the turbine , accurate predictions require fine resolution of the blade leading-edge re gion. This makes performance calculations expensive, and it is probably mor e prudent to use simpler predictive methods. CFD, however, is most useful f or the study of turbine aerodynamics.